1. Field of the Invention
The present invention relates to an improved process for the production of hydroxy compounds by the catalytic hydrogenation of aldehydes such as n-butyraldehyde or n-hydroxybutyraldehyde which result from hydroformylation using a precious metal and phosphorus compound catalyst system. The invention is especially concerned with prolonging the life of the hydrogenation catalyst by treating the aqueous aldehyde hydroformylation stream with an ion exchange resin prior to hydrogenation.
2. Description of the Prior Art
The hydroformylation of olefinic compounds in the presence of precious metal and phosphorus compound catalyst systems is well known. The process is used commercially to manufacture n-butyraldehyde from propylene and n-hydroxybutyraldehyde (4hydroxybutanol) from allyl alcohol. See, for example, U.S. Pat. Nos. 4,238,419, 4,678,857, 4,215,077, 5,290,743 and the like.
In general, the hydroformylation reaction product mixture, which is usually in an organic solvent such as toluene, is contacted with an aqueous extraction stream which extracts the hydroformylation products from an organic phase which contains the catalyst materials. The organic phase can be recycled to the hydroformylation while the aqueous phase is subjected to hydrogenation to convert the contained aldehydes to hydroxy compounds such as n-butanol and 1,4-butanediol. See, for example, Japanese Patent Publication No. 49532/83.
A problem which has existed in this technology has been the tendency for the hydrogenation catalyst, used to convert the aldehydes to hydroxy compounds, to deactivate with time. It is an object of the present invention to provide a process whereby the life of the hydrogenation catalyst can be substantially extended.